A portion of the human population has some malformation of the nasal passages which interferes with breathing, including deviated septa, swelling due to infection or allergic reactions, or inflammation due to changes in atmospheric humidity. A portion of the interior nasal passage wall may draw in during inhalation to substantially block the flow of air. Blockage of the nasal passages as a result of malformation, symptoms of the common cold or seasonal allergies are particularly uncomfortable at night, and can lead to sleep disturbances, irregularities and general discomfort.
In use the external nasal dilator is flexed across the bridge of the nose, extending over the nasal passage outer wall tissues on each side of the bridge, and held thereto by an adhesive. A resilient member (also referred to as a spring member, resilient band, or spring band) is embedded in, or affixed to, the device. The resilient member may be bisected lengthwise into two closely parallel members. Flexure creates spring biasing forces in the resilient member, extending from the middle to the opposite end regions of the device, pulling outwardly to dilate or otherwise stabilize the outer wall tissues of the nasal airway passages. This decreases airflow resistance within the nasal passages and produces a corresponding ease or improvement in nasal breathing.
The resilient member typically produces between 15 grams and 35 grams of resiliency or spring biasing force. Constructing a nasal dilator with less than 15 grams of spring biasing force may not provide suitable stabilization or dilation, while greater than 35 grams would be uncomfortable for most users. Using a more aggressive adhesive, a greater amount of adhesive, or greater adhesive surface area so as to withstand greater spring biasing increases the likelihood of damage to the tissue upon removal of the device.
Examples of present external nasal dilators are disclosed in U.S. Pat. Nos. 6,453,901, D379513, D429332, D430295, D432652, D434146, D437641 and U.S. patent application Ser. Nos. 08/855,103, 12/024,763, 12/106,289, and 12/402,214, the entire disclosures of which are incorporated by reference herein. A minority of the external nasal dilator prior art is adaptable for mass production and thus commercialization in the present consumer retail market. Examples of commercialized nasal dilators, know collectively as nasal strips, include devices disclosed in U.S. Pat. Nos. D379513, 6,453,901, 5,533,503, 5,546,929, RE35408, 7,114,495 and certain devices based upon Spanish Utility Model 289-561 for Orthopaedic Adhesive.
While these example devices provide dilation or stabilization to nasal outer wall tissues in a majority of users, there is a need in the art both to provide variety and complexity in commercially feasible dilator devices and to overcome certain inherent limitations of nasal dilation, including: limited skin surface area adjacent the nasal passages to engage a dilator device; a limited range of spring biasing force that is both effective and comfortable; the dynamic relationship between adhesive engagement and spring biasing peel forces as affects efficacy, comfort and engagement duration; and economically producing complex dilator devices on a mass scale. The present invention discloses novel dilator devices and methods of manufacturing dilator devices which address unmet needs in the art and the limitations of nasal dilation.
A particular inherent limitation of the external nasal dilator is that spring biasing creates peel forces at its opposite end regions, together with some tensile forces, which act to disengage the device from the skin surface. Dilator devices disclosed in U.S. Pat. Nos. 5,533,503 and 6,453,901, and U.S. patent application Ser. No. 12/106,289 include design attributes to mitigate the effect of peel forces or to otherwise shift at least a portion of peel forces into sheer forces. Accordingly, a dynamic relationship exists between dilator design, its flexed spring biasing force, and its efficacy. The present invention builds upon the prior art to address this relationship and further enhance dilator function and comfort.
Nasal dilator devices in the prior art are typically symmetric on each side of the device centerline, which is aligned to the centerline of the bridge of the nose. Each half of the dilator on each side of the centerline is the mirror image of the other. Similarly, each long half of the device, bisected along its length, is typically the mirror image of the other. However, symmetry has not been generally incorporated into dilator design so as to gain manufacturing economy. Of limited exception is where a plurality of dilator devices are die cut on common lines corresponding to their long edges. However, this technique is facilitated by the device having a constant width along its length; a dilator design having wider end regions and a narrower mid section is generally more comfortable and more effective. The present invention discloses novel means of using symmetry in medical device design, and incorporates symmetry into methods of manufacturing dilator devices on common longitudinal lines.
There has also been a continuing need in the art to develop efficient ways of fabricating complex nasal dilator resilient members and incorporating them into mass produced nasal dilators. Complex resilient members are disclosed in the prior art, but not generally practiced in commercially available nasal strip products. For example, FIGS. 12, 17, 20 and 22 of U.S. Pat. No. 6,453,901 illustrate complex resilient member structures in dilator devices, including a method (illustrated in FIG. 16) of forming continuous interconnected resilient members. However, a significant quantity of material extending around and between the interconnected resilient members is lost. The preferred and commonly used material from which resilient members are fabricated carries a significantly greater cost per unit of measure than other materials used in the device. Accordingly, simple resilient member structures prevail in commercialized dilator devices. The present invention discloses means by which to economically mass produce complex resilient member structures with a material usage-to-waste ratio consistent with the fabrication of simpler structures.
The total cost of a medical device is generally the sum of the cost to manufacture (or convert) the device plus the cost of the material used. Material cost includes that which goes into the finished device plus that which is wasted in the converting process. A dynamic relationship exists between converting cost (setup, calibration, registration and alignment, material handling and fabrication time), and material cost; manufacturers (or converters) often obtain efficiency in one area at the expense of the other. Medical devices are typically die cut in cookie-cutter fashion to reduce converting time, but at the expense of material waste extending around and between finished parts. The present invention discloses various methods to reduce material waste while minimizing any additional converting time.
A common practice is to fabricate external nasal dilators having a material layer above as well as below the resilient member. The two layers are die cut simultaneously, largely to shorten converting time. Thus each material layer comprises about 1.66 square inches of material (based on average overall device dimensions of about 2.63″L×0.63″W), for a total of about 3.31 square inches of material per device. The present invention discloses means to reduce material in at least one of the layers with only a modest increase in corresponding converting time.
Similarly, nasal dilator resilient members are traditionally formed from a continuous strand of material equal to each member's finished width. A plurality of strands are slit along common long edges, then separated and repositioned laterally across the fabrication matrix. Repositioning may constitute a separate and additional converting operation, which carries a cost. The present invention discloses means whereby to slit and position strands in the converting process simultaneously, without a separate and additional operation. The present invention further discloses means to re-incorporate potentially unavoidable resilient member material waste into a subsequent fabrication process which yields additional or complementary dilator devices.
Where a nasal dilator resilient member is fabricated to be centered within the peripheral edges of the finished device, material waste can be up to 73%. This manufacturing technique (called island placement) simultaneously die cuts and registers a plurality of spaced apart components along a material strip, or across and along a material web, so that each component (i.e., the resilient member) is centered within the perimeter edges of another plurality of similarly registered components (material layers which form the rest of the dilator). Island placement requires additional material extending along each side of the finished resilient member plus material extending between successive devices fabricated lengthwise end to end. The additional material is used as a matrix by which to space the finished resilient members apart; the wider the matrix, the poorer the usage-to-waste ratio. Once the resilient members are die cut, the matrix is removed as a whole from around and between the spaced apart resilient members and discarded as necessary waste.
By example, a finished resilient member may be about 2.25″ long×about 0.24″ wide, for a total of 0.54 square inches of material. Where resilient members are formed from a continuous strip of material, adding 0.125″ to each long edge of the strip increases strip width to 0.49″. Individual resilient members must also be spaced apart lengthwise by about 3″ from center to center to allow adequate perimeter space to form a finished dilator device being about 2.63″ long. This means 1.47″ sq. (3″×0.49″) of material is used to fabricate and position a resilient member comprising 0.54″ sq. of material. The resulting usage-to-waste ratio is nearly 1:4, where about 27% of the material is used for the finished resilient member and about 73% of the material is wasted. The present invention discloses means to improve resilient member material waste, particularly in the fabrication of complex resilient member structures, where the higher per unit material cost has the greatest impact on manufacturing economy.
Similar to the fabrication of island-placed components, finished nasal strip devices are typically manufactured in a continuous process which spaces one device from another by about 0.125″ on all sides so that material not devoted to the device itself (the waste matrix) can be removed as a whole. Finished devices meant to be packaged in the same operation are spaced even farther apart to provide a suitable contact perimeter around each unit so that upper and lower packaging material webs may form an adequate seal. Again, material from which finished devices or device elements are fabricated is often used as the matrix by which to space finished devices apart. Nasal strips fabricated in closer proximity to each other in order to avoid that material waste are often packaged in a separate, dedicated operation, thus incurring a corresponding cost. The present invention discloses means to fabricate medical devices so as to reduce waste, and to simultaneously space finished devices apart so as to seal the devices between packaging webs, without incurring a separate operational cost or the traditional amount of material waste.